fix(datasource/docker): treat empty string as no architecture

[staticf0x]

Changes

Changed the condition for detecting architecture specific docker images, instead of isString, isNonEmptyString should be used, because certain docker images or OCI artifacts can have it as en empty string (architecture === '' ). In such cases, the meaning is that the image is not supposed to be runnable on a host system.

Copying the full problem description from #40473:

The problem

Beginning on this line: https://github.com/renovatebot/renovate/blob/main/lib/modules/datasource/docker/index.ts#L869 when Renovate tries to determine the image architecture, the following code can fail in a subtle way when trying to update OCI artifacts (not OCI images!) which may or may not have their architecture set to an empty string.

There are two situations that are covered in getDigest():

1. architecture is a string and is one of the GOARCH values, so it then goes to find the arch-specific manifest
2. architecture is null | undefined, so not present in the manifest, so Renovate makes a simple HEAD request to pull the manifest for newTag and done

but the problem arises when architecture is an empty string (architecture === ''). In that case the execution follows to this block:

        if (!digest) {
          logger.debug(
            { registryHost, dockerRepository, newTag },
            'Extraction digest from manifest response body is deprecated',
          );
          digest = extractDigestFromResponseBody(manifestResponse!);
        }

and fails on parsing an empty manifest body:

TypeError: Cannot read properties of null (reading 'body')
    at extractDigestFromResponseBody (/home/renovate/renovate/lib/modules/datasource/docker/common.ts:334:48)
    at DockerDatasource.getDigest (/home/renovate/renovate/lib/modules/datasource/docker/index.ts:1008:49)
    at processTicksAndRejections (node:internal/process/task_queues:105:5)
    at /home/renovate/renovate/lib/util/cache/package/decorator.ts:145:19
    at lookupUpdates (/home/renovate/renovate/lib/workers/repository/process/lookup/index.ts:702:33)
    at /home/renovate/renovate/lib/workers/repository/process/fetch.ts:80:12
    at LookupStats.wrap (/home/renovate/renovate/lib/util/stats.ts:38:20)
    at /home/renovate/renovate/lib/workers/repository/process/fetch.ts:132:23
    at file:///home/renovate/renovate/node_modules/.pnpm/p-map@6.0.0/node_modules/p-map/index.js:139:20

Examples

Taking the Tekton catalog as an example, we can see that some artifacts have architecture set:

$ skopeo inspect docker://ghcr.io/tektoncd/github.com/tektoncd/pipeline/cmd/git-init:v0.37.0 | jq ".Architecture"
"amd64"

while others do not:

$ skopeo inspect docker://ghcr.io/tektoncd/catalog/upstream/tasks/git-clone:0.10 | jq ".Architecture"
""

Context

Please select one of the following:

• This closes an existing Issue, Closes: #
• This doesn't close an Issue, but I accept the risk that this PR may be closed if maintainers disagree with its opening or implementation

Neither applies, this is related to a discussion I opened: #40473 where the problem is described in detail, but haven't received any comments.

AI assistance disclosure

Did you use AI tools to create any part of this pull request?

Please select one option and, if yes, briefly describe how AI was used (e.g., code, tests, docs) and which tool(s) you used.

• No — I did not use AI for this contribution.
• Yes — minimal assistance (e.g., IDE autocomplete, small code completions, grammar fixes).
• Yes — substantive assistance (AI-generated non‑trivial portions of code, tests, or documentation).
• Yes — other (please describe):

I used Cursor (claude-4.5-sonnet) to generate the unit test, which I have checked manually. The code change itself was done by me.

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests, but ran on a real repository, or
• Both unit tests + ran on a real repository

The public repository: https://github.com/staticf0x/mintmaker-test/pull/182/changes

[RahulGautamSingh]

LGTM

[github-actions]

🎉 This PR is included in version 42.93.1 🎉

The release is available on:

• GitHub release
• 42.93.1

Your semantic-release bot 📦🚀